Repair Topics / Engine Sensors-1 / Engine Sensors-2

Engine Sensors - Computer Sensors - ECM Sensors Questions

Question: 1999 Dodge Dakota mileage: 90,000.  You have touched on the subject, but I wonder if you might help me. I have low rpm spark plug knock in my 99 Dakota 4x4.  The dealer says I need higher-octane fuel.  In your FAQ archive, I noticed that you told another Dakota owner to check the EGR valve.  Is 96 octane high enough, or do I need an additive (102 boost, etc)?  This pinging is making me crazy. Thanks!

Answer: The EGR valve can cause the pinging but also check the knock sensor. If the knock sensor is functioning properly, it detects the pinging and retards the timing. Scan your PCM for trouble codes.

Answer: The Mass Air Flow sensor is located inline with the air  intake system.

Question: 1999 Pontiac Grand Am mileage: 92,000.  The crank sensor is bad and needs to be replaced.  I purchased a new crank sensor and a Haynes book for the car.  The Haynes book says that the crank sensor is 0.05 inches from the crankshaft reluctor ring and it protrudes through the engine block; however, I can not locate the sensor anywhere.  The coil packs (the car has a distributorless system) are in the back of the engine and I could not get a good look there, but I have searched everywhere else and have been unsuccessful.   Please tell me where I can find the crank sensor and if there are any useful tips to be employed when replacing the sensor.  Thanks

Answer: The crank angle sensor is located near the coil packs in the side of the block.

Answer: Scan the PCM for trouble code, then try replacing the mass air flow sensor to recheck.

Question: 1999 Mazda B2600 mileage: 93,000. My problem started about 2 months ago and I have not been able to resolve it.  The problem is that occasionally the engine decides to oscillate Rpms when placed in gear (it is a manual transmission), and on some occasions it takes numerous start attempts to get the engine to run on its own and I have to let it warm up for 15 minutes before being able to drive it.  Once running it will vary in power when downshifting, while coming to a stop it will suddenly lurch forward.  This problem is not a constant thing it just comes and goes.  There is no common time of occurrence, such as only when the engine is cold or only hot etc.  I have had a mechanic put the engine on an analyzer and it did not reveal any problems.  I replaced the plugs, wires, fuel filter, catalytic converter, and have added slick 50-fuel treatment along with running only 93-octane gas, none of this has solved the problem.  I am stumped please help with some advice.  Thanks, Ron

Answer: From what you have described, we believe that your problem is a weak oxygen sensor.

Question: 1993 Buick Skylark 6 cylinder mileage: 130,000.  What is an MAF Sensor.  The MAF sensor went bad on my car recently and it cost me $423.00.  What is it and how much do the part alone cost?

Answer:   MAF stands for mass airflow sensor and it measures the quantity of air entering the engine.  You can call the Buick parts department and find out the current cost of the part.

Question: 1994 Chrysler lhs 3.5 V6 mileage: 45,989.  When I come to a stop the tachometer reads about 800 rpm, within 5 seconds I can watch the tachometer drop about 150-200 rpm's.  I have replaced the map sensor.  Where else should I look?  By the way, the computer doesn't show any codes.

Answer:   Try replacing the oxygen sensor, as it appears it may be deteriorating.

Question:   1984 Nissan 300 ZX 3 litre V6 mileage: 112,000 km.  My car is a 1984 Nissan 300 ZX with a three speed automatic with an electronic overdrive for fourth gear.  When I switch the overdrive on, it stays in third gear even when the car is warmed up.  The switch and overdrive solenoid are working but I have been to several auto electricians and they cannot seem to find the fault.  Could you please give me a few suggestions on how to fix my problem?   Thank you. 

Answer:  The overdrive circuit is controlled by the engine temperature sensor to prevent it from going into overdrive when the engine is cold.  If the sensor is faulty, it will not allow your transmission to shift into overdrive.  Also, check the thermostat, if it is stuck open, it will not allow the engine to come up to normal temperature and the transmission will not shift into overdrive.

Question: 2001 Dodge Intrepid mileage: 86,000.  I have reason to believe that I need to replace my Crank Sensor.  How do I locate this under the hood?

Answer:  The crank sensor is located on the passenger side of the engine towards the bottom.

Question: 2003 Dodge Neon, miles: 45,000  My "check engine" light has been on for the past week. I took it to the dealer and they told me it was because of my "upstream oxygen sensor".  What and where is it, and is it something I can change myself?  Is this the same thing as the "oxygen sensor" in my exhaust manifold?

Answer:   Yes, it is in the exhaust manifold.  It is easy to change when the engine is cold.

Question: 1998 Volkswagen Passat mileage: 50,000.  Where is the knock sensor, and how do I replace it.

Answer:   Your engine has two knock sensors, they are located on the front of the engine about center.  Replace them by unplugging the wire connector and removing mounting bolt.

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